Flamestrike
Legend
So no changes (you indicated changes would be in bold)
Honestly, I'd go so far as to limit wizards to only spells from their specialization school. So an Illusionist would be an Illusionist, and an Enchanter would be an Enchanter. No more abjurers clearing the room with a fireball. If you're going to specialize, specialize. Don't half-ass it. I'd definitely add your bonuses to stuff from the specialist school to the mix, though.
It limits them in the sense that 20th level Wizard here (with Int 20) has 6 spells prepared from any school, and 20 prepared from his own school. He retains the flexibility to prepare half a dozen key spells from outside his main school (for counterspell, detect magic, an offensive blasty spell for the non-evokers, mage armor and shield) with the rest all coming from his specialised school.
There is a soft benefit built in (+1 to DCs and attack rolls) to encourage him to use those school spells.
Over the course of his career he'll cast a lot more (school) spells than other spells.